Fabric softener compositions, especially those added in the rinse, are well known. Typically, these compositions comprise a cationic fabric softening agent and perfume. However, frequently these compositions suffer from problems with viscosity stability during storage, especially at storage at, or above, room temperature. The compositions may also suffer with physical stability during storage. Often this is associated with viscosity stability problem.
This has been found to be particularly problematic in fabric softener compositions comprising relatively high levels of fabric softeners actives, e.g. 8% by weight and above, and, of perfume.
It is known to incorporate one or more additional materials, such as silicones, to reduce wrinkling of the fabric during the rinsing and drying stages of the wash.
For example WO-A-96/15309 discloses the use of a combination of a silicone and a film-forming polymer for this purpose. (C) PCT Typical silicones in this application are polydiorganosiloxanes. In many prior art compositions, the silicones are incorporated in the form of an emulsion, which is a micro-emulsion, that is to say the silicone is present as liquid droplets having a droplet size less than the wavelength of visible light and so the emulsion is substantially transparent. However, in a few cases, they are macro-emulsions (e.g. WO-A-97/31997 and WO-A-97/31998). The silicones before emulsification are those having relatively low viscosities, because it is assumed that those with higher viscosities are more difficult to handle during the process of manufacturing the product and are less suited for anti-creasing performance. WO-A-95/24460 discloses a fabric softening composition which contains from about 0.2% to about 20% of a polydimethyl siloxane having a viscosity from about 2 to 5,000 centi-Stokes (cSt).
Our co-pending British patent application 9911942.2 describes fabric softening compositions comprising a cationic fabric softener and an emulsified silicone which has a viscosity before emulsification of 10,000 cSt to 1,000,000 cSt and is a macro-emulsion, and/or, has a median droplet size in the emulsion of at least 0.2 .mu.m and is emulsified with an emulsifier comprising one or more cationic surfactants.
However, the above do not disclose how to provide improved viscosity stability upon elevated temperature storage for fabric softening compositions comprising cationic fabric softeners and perfume.
The present invention seeks to address the problems with viscosity stability upon storage at temperatures above. room temperature, in particular between 25.degree. C. but below 40.degree. C.
It has now been discovered that surprisingly good viscosity stability upon storage at temperatures above room temperature can be achieved by formulating concentrated fabric softening compositions with 3.5 to 15% by weight of a silicone which is emulsified with one or more cationic surfactants and which is incorporated in the form of a macro-emulsion and which silicone has a viscosity of from 10,000cSt to 400,000cSt, and/or the emulsified silicone has a median droplet size of at least 0.2 .mu.m.
References herein to the "emulsified silicone emulsion" are to be construed as being to the emulsion product containing the emulsified silicone. References to the "emulsified silicone" are to be construed as being to the emulsified silicone within the emulsion product that is added to the fabric softening composition.